I bought mine about a year ago to use as a multi-purpose spare/dry lane ball, so for me it's two (and sometimes three) balls in one. Mine has a one inch pin. You can see the layout on the link below, along with the rest of my arsenal.
http://www.putfile.com/album/182521/?action=slideshowI throw Storm, but they don't have a pure urethane ball, so I went with the Groove. The ball was too strong for my needs OOB, so I polished it to 1500 grit. Even with it being urethane and a pancake core, it can still move on the right condition. I've even missed 10-pin spares to the left with this ball, but when I thought it was going in the gutter, it hooks up at just the right point to take out the 10, so that evens it out, lol.
It is a condition-specific ball, which is what I was looking for. One thing I've noticed is this ball hits like a Mack truck. Haven't seen anything like it, urethane-wise, since the original Hammers back in the day. My only problem is lack of confidence using this ball when the lanes break down. Urethane isn't forgiving, so it's also a good training ball to keep you accurate and honest.
Overall I'm satisfied. I was looking for a pure urethane ball and I got exactly what I wanted. So instead of carrying 5 balls, I carry 3. This is my first Big B since I bought a used Rhino Pro Teal back in the day, which was the worst ball I ever owned. Never bought Big B again until the Urethane Groove last year. I like it so much, I'm considering buying more Big B stuff in the future.
Enjoy your Groove, I think you'll like it.